The power supply apparatus such as an adapter is widely used for rectifying and converting AC power into DC power. FIGS. 1(a) and 1(b) are respectively exploded and perspective views of a conventional power supply apparatus. Such power supply apparatus includes an upper housing 1 and a lower housing 2. A space is defined between the upper housing 1 and the lower housing 2 for accommodating a circuit board 3 therein. An AC inlet 4 and other electronic components 30 required for the power supply apparatus are mounted on the circuit board 3. A first concave 11 and a second concave (not shown) are respectively provided on the front side and the rear side of the upper housing 1. A third concave 21 and a fourth concave 22, opposite to the first concave 11 and the second concave, are respectively provided on the front side and the rear side of the lower housing 2. When the upper housing 1 and the lower housing 2 are jointed together, the first concave 11 and the third concave 21 forms a slot for infixing the AC inlet 4 therein to receive external AC power. The circuitry mounted on the circuit board 3 converts the AC power supply into a DC power supply, and the converted DC power is supplied to electrical appliances such as printers, radios and modems.
Referring to FIGS. 2(a) and 2(b), the AC inlet 4 basically includes an insulating main body 40, two power terminals 411, 412 and a ground terminal 413. The power terminals 411, 412 and the ground terminal 413 are located in a cave 41 inside the main body 40 and pass through the apertures (not shown) on the backside surface 401 of the main body 40. The power terminals 411, 412 are respectively coupled with the power pins 431, 432 via rivets 421, 422. The power pins 431, 432 are further inserted into the corresponding pinhole 31, 32 on the circuit board 3 (FIG. 1(a)), and subsequently fixed to the circuit board 3 by welding technique. The power terminals 411 and 412 are utilized to accept electrical signals of AC power through the power pins 431, 432 into the circuit board 3. The ground terminal 413, which is used for accepting a ground signal, is coupled with a ground pin 433 via a rivet 423. The ground pin 433 is essentially L-shaped and includes a first strip 4331 and a second strip 4332, wherein the first strip 4331 and the second strip 4332 are parallel with the backside surface 401 and the topside surface 402 of the main body 40, respectively. In addition, the second strip 4332 has a hole 4331.
Please refer to FIGS. 3(a) and 3(b). The ground pin 433 is grounded by being electrically connected to a ground voltage on the circuit board 3 via a wire 45. The process for fastening the wire 45 onto the ground pin 433 is performed by inserting a bare wire end 451 of the wire 45 into the hole 4331 (FIG. 3(a)) and then applying solder 452 around the hole 4331 to weld the bare wire end 451 (FIG. 3(b)).
It is found that a portion of the solder 452 might be stripped by carelessly pulling the wire 45 or due to the heat transferred from the electronic components 30 in operation. Moreover, the wire 45 will be disconnected with the ground pin 433 such that the grounding effect is largely reduced.